Turbomolecular pump

Abstract

A turbomolecular pump is disclosed which has reduced axial length so as to provide a small-sized pump, and which also has improved stability during high-speed operation, is simple in construction, and is able to operate at much higher speeds than prior art devices. The turbomolecular pump comprises: a cylindrical housing having a plurality of stator vanes provided on the inner peripheral surface thereof, the cylindrical housing having inlet ports and an outlet port; a rotary shaft rotatably supported on the cylindrical casing through bearings; a rotary member fixedly mounted on the rotary shaft and having a plurality of rotor vanes provided on the radially outer peripheral surface thereof, the rotor vanes being interlaced with the stator vanes in a face-to-face relation with each other so that during rotation of the rotor, the rotor and stator vanes cooperate with each other to produce a undirectional flow of a fluid from the inlet ports toward the outlet port; and an electric motor disposed in the cylindrical housing for electromagnetically driving the rotary member to rotate relative to the housing, the motor including a rotor mounted on the rotary member and a stator mounted on the housing in an axially spaced face-to-face relation with the rotor.